Choosing between classic blue or black for your Kaweco fountain pen? Dive into an assortment of hues with Kaweco's Ink Cartridges, offering you a broad spectrum of distinct colours. These cartridges aren't merely about utility, but an exploration of emotion and expression. To ensure the purity of each colour, consider using the Kaweco cleansing syringe when changing between ink colours. It ensures swift and thorough pen cleaning, preventing any unwanted colour mixing.